Andreja Brigić

Terrestrial isopod community as indicator of succession in a peat bog

Abstract Terrestrial isopods were studied in the Dubravica peat bog and surrounding forest in the northwestern Croatia. Sampling was conducted using pitfall traps over a two year period. Studied peat bog has a history of drastically decrease in area during the last five decades mainly due to the process of natural succession and changes in the water level. A total of 389 isopod individuals belonging to 8 species were captured. Species richness did not significantly differ between bog, edge and surrounding forest. High species richness at the bog is most likely the result of progressive vegetation succession, small size of the bog and interspecific relationships, such as predation. With spreading of Molinia grass on the peat bog, upper layers of Sphagnum mosses become less humid and probably more suitable for forest species that slowly colonise bog area. The highest diversity was found at the edge mainly due to the edge effect and seasonal immigration, but also possibly due to high abundance and predator pressure of the Myrmica ants and lycosid spiders at the bog site. The most abundant species were Trachelipus rathkii and Protracheoniscus politus, in the bog area and in the forest, respectively. Bog specific species were not recorded and the majority of the species collected belong to the group of tyrphoneutral species. However, Hyloniscus adonis could be considered as a tyrphoxenous species regarding its habitat preferences. Most of collected isopod species are widespread eurytopic species that usually inhabit various habitats and therefore indicate negative successive changes or degradation processes in the peat bog.

Taxon specific response of carabids (Coleoptera, Carabidae) and other soil invertebrate taxa on invasive plant Amorpha fruticosa in wetlands

False indigo (Amorpha fruticosa L.) is an invasive exotic plant introduced to Europe in the early eighteenth century. Its spread has been rapid, particularly in disturbed wetland habitats, where it forms dense impermeable monospecific stands and modifies habitat conditions. The impact of A. fruticosa on native plant communities has been well analyzed, however knowledge concerning the possible effects on soil invertebrates and particularly carabid beetles is completely lacking. This study analyzed the impact of an A. fruticosa invasion on carabid beetles and other soil invertebrates. Soil fauna was sampled by pitfall traps at natural habitats, initially colonized by A. fruticosa, and habitats largely invaded by A. fruticosa. In total 2,613 carabid beetles belonging to 50 species and 72,166 soil invertebrates were collected. The invasion of A. fruticosa strongly affected the carabid beetle species composition, which clearly differed between all studied sites. Widespread euritopic carabid beetle species showed positive responses to A. fruticosa invasion, while the activity density of open habitat species strongly declined. Mean individual biomass was significantly higher at invaded sites due to increased incidence of large carabids (genus Carabus Linné, 1758). Carabid beetle activity density and abundance of soil invertebrates were considerably higher at invaded sites than in natural sites. Conversely, the impact of A. fruticosa on carabid beetle species richness and diversity was less pronounced, most likely due to immigration from adjacent habitats. Changes in carabid beetle species composition and abundance of soil invertebrates were most likely due to changes in vegetation structure and microclimate. The results suggest that A. fruticosa invasion considerably affected carabid beetles, an insect group that is only indirectly related to plant composition. Therefore, severe future changes can be expected in invertebrate groups that are closely related to plant composition, since A. fruticosa cannot be completely removed from the habitat and covers relatively large areas.

Adriatic coastal plant taxa and communities of Croatia and their threat status.

Abstract Coastal ecosystems of Croatia have recently become highly threatened because of the sudden increase in tourism, building by the shore and other anthropogenic activities. Based on the phytosociological research so far, 20 plant communities of halophilous vegetation have been established, sorted into 10 classes. Presented in this paper, for the first time, are 129 taxa of vascular flora typical of the coastal belt. To each species are assigned: conservation status, endemic status, affinity to habitat type, plant community preference and site frequency. Because of the karstic geological substrate, the coastal region of the eastern Adriatic consists predominantly of maritime rocks. Among the most endangered habitat types are sandy shores, maritime shingle and saltmarshes.

Extreme land-cover and biodiversity change as an outcome of land abandonment on a Mediterranean island (eastern Adriatic)

Abstract Understanding land abandonment and the resulting changes in land cover provides data for suitable reaction to habitat and species losses this process brings. This study aimed to define land-cover types and their biodiversity, record spatio-temporal changes and detect the trajectories and magnitude of these changes. The study was conducted on the island of Molat in the eastern Adriatic Sea. Land cover was defined for different years (1910, 1959, 1986, 2006) using remote sensing and recent vegetation sampling. The obtained land-cover maps were used for spatio-temporal analysis of land-cover change. Open vegetation units of rocky grassland, mesophilous grasslands and farm land dominated in 1910, covering 90% of the island. The observed changes occurred in trajectories through semi-open towards closed vegetation. In 2006, closed vegetation dominated, covering approximately 70% of the island area. The overall land-cover change was extreme, occurring over 90% of the island surface. Biodiversity analysis was related to the present land-cover types and change trajectories, and showed a considerable decline of species richness towards closed vegetation types. All observed changes were correlated to island depopulation and land abandonment. Re-population and encouragement of agro-pastoral activities should reduce habitat and species loss in the process of secondary succession.

Spatial distribution and seasonal changes of mayflies (Insecta, Ephemeroptera) in a Western Balkan peat bog

Abstract Peat bogs are unique wetland ecosystems of high conservation value all over the world, yet data on the macroinvertebrates (including mayfly assemblages) in these habitats are still scarce. Over the course of one growing season, mayfly assemblages were sampled each month, along with other macroinvertebrates, in the largest and oldest Croatian peat bog and an adjacent stream. In total, ten mayfly species were recorded: two species in low abundance in the peat bog, and nine species in significantly higher abundance in the stream. Low species richness and abundance in the peat bog were most likely related to the harsh environmental conditions and mayfly habitat preferences. In comparison, due to the more favourable habitat conditions, higher species richness and abundance were observed in the nearby stream. Three of the recorded species, Caenis luctuosa from the peat bog, and Eurylophella karelica and Leptophlebia marginata from the stream are new records for the Croatian mayfly fauna. Typical Central European life cycle patterns were confirmed for several species (e.g. Baetis vernus, Nigrobaetis niger, Electrogena ujhelyii), while for several others (e.g. Habrophlebia fusca, Paraleptophlebia submarginata) some discrepancies were observed. Therefore, these results provide new and valuable information on the ecology of mayflies in peat bog habitats.

Ecology, biology and conservation of Pterostichus rhaeticus Heer, 1837 (Coleoptera: Carabidae) at the edge of its distribution range, in the Western Balkans

Abstract Pterostichus rhaeticus is widely distributed in northern and central Europe and has now been recorded for the first time in Croatia, and this record represents its southeasternmost distribution point. This species was only recently separated from the very common and widespread Pterostichus nigrita Paykull, 1790. These two sibling species differ in a few morphological features and can be certainly distinguished by the form of male and female genitalia. Therefore, we measured a few morphometric features, e.g. body length, elytrae length and width, male right paramere and female eighth abdominal sternite. In general, P. rhaeticus is significantly smaller and narrower than P. nigrita. However, in mixed populations, the differences in body size, length and width of elytrae were not observed and the overlap in sizes is considerable. Additionally, we noticed that the range edge individuals of P. rhaeticus are larger compared to individuals in central Europe. Most of the individuals of both species can be clearly and immediately identified by the shape of their genitalia, but in mixed populations these differences are possibly not so obvious, and measurements are necessary. P. rhaeticus is a tyrphophilous species that was exclusively found at three peatlands in Croatia. It was found in the open peat bog centre and adjacent shaded habitats, in both acidic peaty and alkaline soils with high soil humidity. According to present knowledge, this species can be considered an indicator species of peatland habitats in Croatia. These distinctive habitats are highly endangered in the Western Balkans, and therefore the survival of this and other bog-specific species depends on active conservation and protection measures.

Rasprostranjenost kopnenog jednakonošca Hyloniscus adonis (Verhoeff, 1927) (Isopoda: Oniscidea) u Hrvatskoj

This paper presents the distribution of the terrestrial isopod Hyloniscus adonis (Verhoeff, 1927) in croatia. It was recorded for the first time at the edge of Dubravica peat bog and the adjacent forest. Additionally, it was collected at the edges of Đon močvar peat bog. Revision of the terrestrial isopod collection of the Croatian Biospeleological Society revealed that this species also occurs in central and eastern part of Croatia. Our results reveal that H. adonis is a hygrophilic species inhabiting various types of forests in the colline and montane belts. It prefers humid soils with thick litter and humus layers and most probably seldom leaves its shelter. H. adonis is extremely rare in open bog habitats, most likely due to the harsh environmental conditions (e.g. high soil humidity, low pH values) and can be considered as a tyrphoxenous species. Additionally, it was also found in the entrance zones of caves, most likely due to the favourable microclimatic conditions. It seems to be a temporary cave dweller and can be classified as a trogloxenous species.

Water mite (Acari: Hydrachnidia) diversity and distribution in undisturbed Dinaric karst springs

Large undisturbed karst springs in the Dinaric region are particularly interesting and extremely valuable and rare ecosystems, housing diverse and yet undiscovered water mite species. The complex life history traits of water mites include several life stages that are interconnected with other freshwater arthropod groups, making them important components of freshwater fauna. This study examined whether the differences in water mite assemblages between Mediterranean and alpine karst springs were driven by seasonal and/or regional changes in environmental conditions. The first ecological data on water mite dynamics and distribution in the Dinaric region of Croatia are presented. Water mites were represented by 11 taxa, decreasing in taxon richness from alpine to Mediterranean springs. Spatial patterns of water mite assemblages at the regional scale were best explained by water temperature, dissolved oxygen and water velocity. Pseudotorrenticola rhynchota and Oxus setosus were exclusively found in springs with higher water temperature and velocity, whereas the genera Aturus sp. and Woolastookia rotundifrons were exclusively recorded in the alpine springs, where oxygen concentrations were significantly higher. Atractides sp., Lebertia sp. and Sperchon sp. were recorded in most springs. Water mite abundances had a summer peak in the Mediterranean region, whereas two smaller peaks were observed in the spring and fall in the alpine region. Regional differences in the seasonality of water mite abundance were most likely patterned by the emergence of insect crenofauna.

First record of Apristus europaeus Mateu, 1980 (Coleoptera, Carabidae) in Croatia

Apristus europaeus was recorded for the first time in Croatia. It was found in the dry river bed of the temporary Krčić River (Dalmatian Zagora region), situated beneath the Dinara Mountains. This record represents the southeasternmost distribution border of this species in Europe. Apristus europaeus was sampled with pitfall traps in July 2014. The substrate was composed of boulders, without mosses or algae. Microclimatic conditions were unfavourable for soil invertebrates, since the dry river beds were exposed to intense solar radiation and wind. Our findings show that A. europaeus could quickly recolonize new and unstable habitats, implying that it has a high dispersal capacity. However, this study raises the question of the A. europaeus habitat preference, for in previous studies, it was characterised as a stenotopic hygrophilous species inhabiting the banks of flowing waters.

Morphometric variability and life history traits of the rare Paramogoplistes novaki in comparison to Mogoplistes brunneus (Orthoptera: Mogoplistidae)

Summary In this study, morphometric and life history traits were compared between two species of scaly crickets – Paramogoplistes novaki (Krauss, 1888) and Mogoplistes brunneus Serville, 1838. Crickets were collected along the Krčić River in SE Croatia using pitfall traps. In total, 37 P. novaki and 105 M. brunneus specimens were included in the analyses. Diagnostic traits such as total body length and pronotum length to width ratio proved to be unreliable particularly in differentiating females of the two species. On the other hand, subgenital plate shape turned out to be useful in distinguishing P. novaki from M. brunneus in all stages. Several new differential morphometric traits were found in adults – subgenital plate length, width and length to width ratio. Higher variability of morphometric traits between the sexes was recorded in M. brunneus than in P. novaki, one of the cues indicating possible neotenic origin of the latter. The activity period of P. novaki was shorter and more autumn-oriented than the activity period of M. brunneus. Their surface activity maxima exhibited clear temporal separation, likely to avoid competition due to niche overlapping. Sex ratio was female-biased in both species, pronouncedly so in M. brunneus, probably indicating higher activity of females due to more frequent foraging and/or seeking for oviposition sites. The current study represents a step forward in understanding morphometric variability and life history of these two little-known scaly cricket species.